composer require smartselling/fapi-client 

$fapi = new FAPIClient('username', 'API token'); $fapi->invoice->getAll(); // returns all invoices $fapi->invoice->get(123); // returns invoice #123 $fapi->invoice->search(['client' => 123]); // returns invoices of client #123 $fapi->client->searchOne(['email' => 'johndoe@example.com']); // returns client by email